# Boiling And Melting Points Of A Substance

Previous Topic : Precipitation And Test For Impurities

# Boiling And Melting Points Of A Substance

## Boiling Point Of A Substance

what is a boiling point?

Boiling point is the point or stage at which a substance starts to boil. I believe we all know the meaning of “boil”, when heat is apply to a water on trying to boil it and after few minutes you put your finger in it and you felt warmth, that doesn’t mean the water is boiling, water boils at 100°C, so before you can see a water boiling that means the water is at 100°C, but if the water contain impurities it will not boil at 100°C it will boils at temperature higher than 100°C, because impurities increases boiling point of a substance,top↑

Please NOTE : no matter how long a pure water boils it temperature will never pass 100°C,
What am saying is this, when heat is apply to a water of zero impurities, the water will boils at 100°C and if you keep applying heat to the water, it temperature will never pass 100°C but it mass will changes because for that time that the water has been boiling, a lot of water particles have leave the surface of the water (evaporation) due to the applied heat.

So when you boils pure water ones it temperature reaches 100°C it will be steady there, no matter how long the water keeps boiling but it mass will changes, that is, the mass will have decreases due to evaporating of water molecules.top↑

Now let talk about melting point,

## Melting Point Of A Substance

What is melting point?
Melting point is the point or stage at which a substance starts to melt from solid state to liquid state.

### Melting Point Of An Ice Block

Let me use ice block as an example,
Everybody know ice block right?
Explanation :
We all know a block of ice is in solid form, so melting point is the point or stage at which a block of ice starts to change to water, that is, when a substance in solid form starts to change to liquid form.top↑

NOTE : liquid start freezing at 0°C to negative(-)°C, what am saying is water will start freezing at 0°C(start freezing not already froze) but when you are seeing negative sign(-) in front of a temperature, that means the water has frozed.

Impurities reduces or lower melting point,
Try and praticalise this on your own,

Prepare two ice blocks at the same time and after they have froze, rub one of the ice block with salt and see which one of the ice block will melt faster,
It is the one rub with salt because the salt serve as an impurities and impurities lower the melting point of a substance,
This technique is applied in some countries like America , during winter they sprinkle salt on the road surface, so as to make the ice melt faster by lowering the melting point of the ice by sprinkling salt on the road.top↑
And if you don’t have chance to practise this what am saying is that:

Impurities lowers melting point of a substance.

Another process that lowers melting point is Reggelation by application of pressure, this one is under physics.

Thank GOD finally we through with separating techniques, our next topic will be on ELEMENTS, SYMBOLS AND VALENCY, where will be talking about first 20 elements.top↑

Thank you for always reading, feel free to ask me any question via the comment box or ask question page and I will be happy to answer your question and take the session again if necessary, your comment notifications is like a bank alert to me so don’t forget to write something.top↑
Our Contact Page or will you like to know more About Our Tutors

Next Topic : Formulae And Valency